Okay, first: there's a problem with the idea that in vitro embryos can be called "natural." However, the rest is ethical.
news@nature.com carries a report that does what Lanza did not: shows that single cells (blastomeres) from embryos can grow to yield embryonic stem cells without the intentional killing of an embryo.
The embryos were observed for 2 days, if there was no cell division, the embryos were deemed to be "dead."
If the finding is confirmed, and the cells are pleuripotent (will give rise to embryonic stem cells, but no to the trophoblast or placenta cells, and so is no longer an embryo developing into a fetus, then a neonate, etc.), then the use of the cells would be ethical. Just as it's ethical to "use" cadavers for medical research or teaching, with the informed consent of the surrogate decision makers (i.e., parents.).
"Fewer than half of human eggs fertilized in vitro do not develop to the 'blastocyst' stage, which is required for implantation," says Miodrag Stojkovic, who led the project at the University of Newcastle in the UK. He is now deputy director of the Principe Felipe Research Centre in Valencia, Spain. "There are many different reasons why they don't survive."
Arrested development
Stojkovic used 161 donated embryos in his study, which is scheduled to be published in Stem Cells1. The embryos came from two local in vitro fertilization clinics. Of these, 29 were developing, 119 'arrested' (stopped dividing) 3 to 5 days after fertilization, and 13 arrested 6 to 7 days after fertilization.
There is the problem of the 29 which were still developing.
The researchers evidently overcame the problems that Lanza had with the necessity of growing the cells with the original embryo.
Unfortunately, this will probabley turn out to be a distraction, used to "prove" that the embryonic stem cell researchers were looking in the right places, to begin with.
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